The insects are a sign of the plant in distress, they aren't the cause of it.
Did you plant the trees? Do you know about the problem that often occurs when trees are planted too deep in the ground? In addition to the sick tree treatment, you need to expose the trunk flare if it is buried. Take a look at Howard's instructions for planting trees
to see if your trees need to have some dirt CAREFULLY removed from around the base.Root flare newsletter
Does it look like this:
or this? (The correct appearance is this one below)
You also need to consider what has been used near the tree - has it been in an organic program? Are chemicals or herbicides being used in the area? Do you have a sprinkler system - is the tree possibly getting too much or too little water?
Check for organic businesses in your area. If you are serious, the fastest approach might be to consult a couple of arborists and see what they say, get a couple of bids for the work. http://www.dirtdoctor.com/organic/garden/advance_business_listings/